如果应用关闭，使用POP-UP进行Fcm通知

i am using FCM Notification and its working perfectly. issue is i am unable to show pop-up notification if app is close. notification only shows in notification history. i want to show pop-up like whatsapp if app is not open.

If app is open. then it works perfectly. onMessageReceived method only calls when app is open.

Here is my code.

MyFirebaseMessagingService.java

public class MyFirebaseMessagingService extends FirebaseMessagingService {
NotificationCompat.Builder mBuilder;

@Override
public void onMessageReceived(RemoteMessage remoteMessage) {
    Map<String, String> data = remoteMessage.getData();

    if (remoteMessage.getNotification() != null) {
        String noti_body = remoteMessage.getNotification().getBody();
        String noti_title = remoteMessage.getNotification().getTitle();
       mBuilder = new NotificationCompat.Builder(this, "M_CH_ID")
                    .setSmallIcon(R.mipmap.logo)
                    .setContentTitle(noti_title)
                    .setContentText(noti_body)     
                .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.logo))
                   .setColor(getResources().getColor(R.color.colorAccent))
                    .setDefaults(Notification.DEFAULT_ALL)
                    .setPriority(NotificationCompat.PRIORITY_HIGH)
                    .setVisibility(NotificationCompat.VISIBILITY_PUBLIC)
                    .setAutoCancel(true);

    Intent intent = new Intent(this, MainActivity.class);
    @SuppressLint("WrongConstant")
    PendingIntent pi = PendingIntent.getActivity(this, 0, intent, Intent.FLAG_ACTIVITY_NEW_TASK);
    mBuilder.setContentIntent(pi);
    NotificationManager mNotificationManager =
            (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
    mNotificationManager.notify(0, mBuilder.build());
}
}

php code:

$data = array
(
  "activity" => $activity_to_open
);

$notification = array('title' =>$title , 'body' => $message,'click_action' => '.MainActivity' ,'sound' => 'default', 'badge' => '1');    
$arrayToSend = array('to' => $token, 'notification' => $notification,'data' => $data, 'priority'=>'high');